The present invention relates generally to a seat for mass transit vehicles such as buses or subway cars, and more particularly to seats of this type having grab bars extending upwardly from the top of the seat back.
Conventionally, these grab bars have been made of steel tubing. A mass transit vehicle, like any other vehicle, may have to stop suddenly, or may lurch forward, causing the occupant of a seat in the vehicle to be propelled forwardly and downwardly from the waist in such a manner as to strike his head or other parts of his body on the grab bar of the seat in front of him.
To overcome this problem, cushioned grab bars have been proposed. Typically, a cushioned grab bar comprises a metallic, tubular inner member covered with an outer layer of resilient cushioning material such as polyvinyl chloride plastic, of suitable softness and impact resistance.
The areas of the grab bar where impact by the head of a seat occupant is most likely are the back and top or outside of the grab bar, with the least likely area of impact being the bottom or inside of the grab bar. Accordingly, the resilient cushioning material should be thicker at the areas where impact is most likely and relatively thin at the areas where impact would not occur.
Problems arise in maintaining the outer layer of resilient cushioning material in proper peripheral registry with the inner tubular member so that the relatively thicker parts of the cushioning layer are maintained at the areas where impact is most likely. Absent a proper bond between the two, there may be slippage of the outer layer of resilient cushioning material relative to the inner tubular member. One approach to this problem is to provide an inner tubular member having a rectangular cross-section and an extruded outer tube of resilient cushioning material also having a rectangular cross-section and to slide the outer tube over the rectangular inner tubular member. A drawback to this approach is that rectangular steel tubular members are relatively expensive compared to round steel tubular members.
Another conceivable approach is to use a round tubular inner member, apply adhesive to the outside of it and then try to slide an extruded tubular layer of resilient cushioning material over the round tubular inner member. However, it is difficult to fit an outer extruded layer of resilient material over an inner tubular member when the latter was adhesive applied to it. The adhesive is setting or curing all the while the fitting operation is in progress, and this impedes the fitting operation as well as a proper peripheral registry of the outer layer relative to the round inner member, or else the fitting operation impedes the curing of the adhesive so that a proper bond is not obtained.
Another consideration arises in connection with the manner in which the grab bar is assembled to the seat. The seat usually comprises a tubular back frame having a pair of upstanding tubular side rails connected by a top back rail. A plastic shell is attached to the back frame, with a flange extending from the shell and overlapping the top back rail. The upstanding side rails are open at their top ends to receive terminal parts of the grab bar. The top flange on the plastic shell has a cut away portion to accommodate the grab bar where it enters the upstanding side rail of the seat frame. Thus, the side rails of the seat frame, the plastic seat shell, and the cushioned grab bar all come together at a pair of locations on the seat back. At these locations, there can be exposed edges of the plastic shell's cut away portion, or of the tubular side rails at their upper open ends. Exposed edges are undesirable from an aesthetic standpoint and also because a seat occupant can catch and tear his clothing on the exposed edges of the side rails. One approach to resolving this problem is to grind or polish or otherwise smooth or round the exposed edges, but this is relatively expensive.